U.S. Pat. No. 5,633,262 disclosed a novel quinoline(naphthyridine) carboxylic acid derivatives and pharmaceutically acceptable salts thereof. These compounds are antibacterial agents. Among them gemifloxacin, chemically 7-[3-(Aminomethyl)-4-(methoxyimino)-1-prrolidinyl]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid is a third generation fluorinated quinolone antibacterial agent. Gemifloxacin is represented by the following structure:

Processes for the preparations of gemifloxacin and related compounds were disclosed in U.S. Pat. No. 5,633,262 and PCT Patent Publication No. WO 01/18002 A1.
One object of the present invention is to provide a novel process for preparing gemifloxacin and pharmaceutically acceptable acid addition salts of gemifloxacin in high yield using novel intermediates.
Another object of the present invention is to provide a process for the preparation of amorphous gemifloxacin.
Another object of the present invention is to provide novel hydrates of gemifloxacin, processes for preparing them and pharmaceutical compositions comprising them.
Another object of the present invention is to provide a novel crystalline gemifloxacin lactic acid salt, process for preparing it and a pharmaceutical composition comprising it.
Another object of the present invention is to provide a novel crystalline gemifloxacin formic acid salt, process for preparing it and a pharmaceutical composition comprising it.
Another object of the present invention is to provide a process for the preparation of infusion solutions of gemifloxacin.